Direction sensor including first and second detecting circuits and first and second magnetic bias application parts

ABSTRACT

A direction sensor has first and second bridge circuits, each of the bridge circuits including at least two detecting elements formed on a main surface of a substrate and connected in series, their longitudinal directions crossing each other. The sensor also has first and second magnetic bias application parts respectively facing toward the first and the second bridge circuits. The directions of the magnetic fields of the magnetic bias application parts are different from each other. The direction sensor does not require a holder or a coil, so that miniaturization of the sensor is feasible.

TECHNICAL FIELD

This invention relates to a direction sensor to be used for variouselectronic instruments and a production method thereof.

BACKGROUND ART

FIG. 10A is a perspective view of an ordinary direction sensor, and FIG.10B is a sectional view of the same taken along the line 10B—10B. Theordinary direction sensor has:

bridge circuit 3 including four detecting elements 2A to 2D, placed onan upper surface of substrate 1;

holder 4 holding substrate 1 and covering substrate 1 including bridgecircuit 3; and

first coil 5A and second coil 5B forming magnetic bias applicationparts, made of conductive wires, winding up around holder 4 withpredetermined winding numbers, and being at right angles to each other.

In the ordinary direction sensor, substrate 1 including detectingelements 2A to 2D is held by holder 4, and first coil 5A and second coil5B wind around holder 4. Because of this structure, the ordinarydirection sensor is large and it is difficult to miniaturize.

SUMMARY OF THE INVENTION

A direction sensor in the present invention has a first detectingcircuit including at least two detecting elements mounted on a mainsurface of a substrate, a second detecting circuit constitutedidentically with the first circuit, a first magnetic bias applicationpart disposed in a position facing the first detecting circuit, and asecond magnetic bias application part disposed in a position facing thesecond detecting circuit. The second magnetic bias application partgenerates a magnetic field in a direction different from a magneticfield generated by the first magnetic bias application part.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a direction sensor in accordance with afirst exemplary embodiment of the present invention.

FIG. 1B is an exploded perspective view of the direction sensor inaccordance with the first exemplary embodiment of the present invention.

FIG. 2 is a sectional view of the direction sensor in accordance withthe first exemplary embodiment of the present invention, taken along theline 1B—1B of FIG. 1A.

FIG. 3 is a plan view of an upper surface of first and second bridgecircuits, main parts of the direction sensor in accordance with thefirst exemplary embodiment of the present invention.

FIG. 4 is an electric circuit diagram of the first bridge circuit, themain part of the direction sensor in accordance with the first exemplaryembodiment of the present invention.

FIG. 5 is a graphical illustration showing a relation between a magneticfield strength of the first and second magnetic bias application partsand a variation of detected direction on the direction sensor inaccordance with the first exemplary embodiment of the present invention.

FIG. 6 is a sectional view of another direction sensor in accordancewith the first exemplary embodiment of the present invention.

FIG. 7 is a sectional view of a direction sensor in accordance with asecond exemplary embodiment of the present invention.

FIG. 8 is a plan view of an upper surface of first and second bridgecircuits, main parts of a direction sensor in accordance with a thirdexemplary embodiment of the present invention.

FIG. 9 is a circuit diagram of a varied type of the first detectingcircuit of the direction sensors in accordance with the first to thethird exemplary embodiments of the present invention.

FIG. 10A is a perspective view of an ordinary direction sensor.

FIG. 10B is a sectional view of the ordinary direction sensor takenalong the line 10B—10B of FIG. 10A.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Exemplary embodiments of the present invention will be demonstratedhereinafter using the drawings. A same reference mark is used for anidentical constituent, and detailed explanation of it is omitted.

First Exemplary Embodiment

FIG. 1A is a perspective view of a direction sensor in accordance with afirst exemplary embodiment of the present invention 1. FIG. 1B is anexploded perspective view of the same. FIG. 2 is a sectional view of thesame, taken along the line 1B—1B, and FIG. 3 is a plan view of first andsecond bridge circuits, main parts of the same. FIG. 4 is an electriccircuit diagram of the first bridge circuit of the direction sensor inaccordance with the first exemplary embodiment.

As shown in FIG. 1A to FIG. 3, the direction sensor in the firstexemplary embodiment has:

substrate 11,

first bridge circuit 13 (a first detecting circuit) having firstdetecting element 12A to fourth detecting element 12D, formed on anupper surface of substrate 11,

second bridge circuit 14 (a second detecting circuit) having fifthdetecting element 12E to eighth detecting element 12H,

insulating layers 15A and 15B respectively deposited on upper surfacesof first bridge circuit 13 and second bridge circuit 14,

first magnetic bias application part 16 and second magnetic biasapplication part 17 (hereafter, each called application part)respectively disposed on upper surfaces of insulating layers 15A and15B, facing toward first bridge circuit 13 and second bridge circuit 14,respectively,

cover layers 21A and 21B composed of, such as, epoxy resin and siliconresin respectively deposited on upper surfaces of first application part16 and second application part 17.

First and second application parts 16 and 17 are constituted so thattheir generated magnetic fields are directed substantially 90° differentfrom each other, as shown by arrow marks 31 and 32 in FIG. 3.

The constituent members are explained hereinafter.

Substrate 11 is in a rectangular shape and made of an insulatingmaterial such as alumina. A glass glaze layer is preferably formed on amain surface of the substrate because it is easy to get a smooth surfaceof the layer, and therefore, it makes it easy to form first bridgecircuit 13 and second bridge circuit 14 thereon.

First bridge circuit 13 is composed of first detecting element 12A,second detecting element 12B, third detecting element 12C and fourthdetecting element 12D. First detecting element 12A to fourth detectingelement 12D are made of, such as, a strong-ferromagnetic thin film or anartificial lattice multilayer field folded multiple of times. Theferromagnetic thin film is composed of NiCo, NiFe, or the like, whichchanging rate of resistance value reaches a peak when an outsidemagnetic field is vertically applied. By folding the film multipletimes, the number of lines of the terrestrial magnetism crossing thefilm is increased, so that the changing rate of the resistance valuebecomes high, improving a terrestrial magnetism detecting sensitivity.

First detecting element 12A and second detecting element 12B areelectrically connected in series, and third detecting element 12C andfourth detecting element 12D are also connected in series. The seriescircuit of first detecting element 12A and second detecting element 12Band the series circuit of third detecting element 12C and fourthdetecting element 12D are electrically connected in parallel. The jointpart of first detecting element 12A and second detecting element 12B isconnected to first output electrode 20A, and the joint part of thirddetecting element 12C and fourth detecting element 12D is connected tosecond output electrode 20B.

Longitudinal directions in the patterns of first detecting element 12Aand second detecting element 12B are different by substantially 90°.Regarding third detecting element 12C and fourth detecting element 12D,the arrangement is similar to that of elements 12A and 12B. Thelongitude directions in the patterns of first detecting element 12A andfourth detecting element 12D are in parallel. Regarding second detectingelement 12B and third detecting element 12C, the arrangement is similarto that of elements 12A and 12D.

Further, first detecting element 12A and third detecting element 12C areconnected to input electrode 18A, and second detecting element 12B andfourth detecting element 12D are connected to ground electrode 19A.

Thus, first detecting element 12A to fourth detecting element 12Dconstitute a full bridge as shown in FIG. 4. A variation of adifferential voltage between two output voltages at first outputelectrode 20A and second output electrode 20B is increased with aneffect of the bridge circuit, so that compass direction is preciselyidentified. Further, because noise from the two output voltages canceleach other, a dispersion of identifying direction due to the noiseremains small.

Moreover, the longitudinal directions of detecting element 12A to fourthdetecting element 12D are all angled 45° to a direction of the magneticfield produced by first application part 16. By constituting like this,the resistance values of first detecting element 12A to fourth detectingelement 12D are considered to change linearly with the change of themagnetic field. Therewith, compass direction is easily calculated by thedifferential voltage. In this exemplary embodiment, the longitudinaldirections of first detecting element 12A to fourth detecting element12D are each angled by 45° to the magnetic field generated by firstapplication part 16. If the angle is set at 0° or 180°, the magneticfield generated by first application part 16 does not affectively changethe resistance value of the detecting elements, namely it does not actas a bias magnetic field. Because of the reason, 0° and 180° aredesirably avoided, if not 45°.

Input electrode 18A, ground electrode 19A, first output electrode 20A,and second output electrode 20B are all composed of silver, silverpalladium or the like.

Second bridge circuit 14 is similarly structured to first bridge circuit13, and has fifth detecting element 12E, sixth detecting element 12F,seventh detecting element 12G and eighth detecting element 12H, and isconnected to input electrode 18B, ground electrode 19B, third outputelectrode 20C and fourth output electrode 20D.

These constituent members are corresponding, like fifth detectingelement 12E of second bridge circuit 14 to first detecting element 12Aof first bridge circuit 13. Similarly, sixth detecting element 12Fcorresponds to second detecting element 12B, seventh detecting element12G to third detecting element 12C, eighth detecting element 12H tofourth detecting circuit 12D, input electrode 18B to input electrode18A, ground electrode 19B to ground electrode 19A, third outputelectrode 20C to first output electrode 20A, and fourth output electrode20D to second output electrode 20B.

Still further, input electrode 18A and input electrode 18B areelectrically connected and ground electrode 19A and ground electrode 19Bare also electrically connected. Thus, first bridge circuit 13 andsecond bridge circuit 14 are electrically connected in parallel.

Input electrodes 18A and 18B, ground electrodes 19A and 19B, firstoutput electrode 20A, second output electrode 20B, third outputelectrode 20C and fourth output electrode 20D are all exposed forinputting or outputting signals from the outside.

Insulating layer 15A is deposited on the upper surface of first bridgecircuit 13, and insulating layer 15B on the upper surface of secondbridge circuit 14. The layers are composed of a material having aninsulating characteristic, such as SiO₂, alumina epoxy resin or siliconresin. They electrically insulate first and second bridge circuits 13and 14 from first and second application parts 16 and 17. Insulatinglayer 15A covers first detecting element 12A to fourth detecting element12D and insulating layer 15B covers fifth detecting element 12E toeighth detecting element 12H.

If SiO₂ is used for insulating layers 15A and 15B, and if CoPt alloy isused for first and second application parts 16 and 17, intimacy ofcontact of the insulating layers with first and second application parts16 and 17 is strengthened, thereby reliability including humidityresistance is improved and cost of the device is reduced.

First application part 16 is disposed on the upper surface of insulatinglayer 15A facing toward first bridge circuit 13, and second applicationpart 17 is disposed on the upper surface of insulating layer 15B facingtoward second bridge circuit 14. These parts are made of magnet such asCoPt ally, CoCrPt alloy or ferrite of which a magnetic field is alignedin one direction. First application part 16 entirely covers first bridgecircuit 13, and second application part 17 entirely covers second bridgecircuit 14. Directions of the magnetic fields produced by firstapplication part 16 and second application part 17 are substantially 90°different as mentioned above. First and second application parts 16 and17 generate magnetic field in a strength of 5 to 20 Oe.

Next, the reason why the strength of the magnetic field is set in 5 to20 Oe is explained.

FIG. 5 is a graph showing a relation between a magnet field strengthgenerated by first and second application parts 16 and 17 and adispersion of detected direction. In the graph, allowable dispersion inthe detected direction is shown to be 7°, which is a maximum allowabledispersion in detecting 36 points of compass direction.

As is evidently shown in FIG. 5, the dispersion in the detecteddirection is reduced between the magnetic field strength in 5 to 20 Oeand where the direction is more precisely identified.

Setting in above range, since the magnetic field strength is set 20 Oeat most, a difference between a field strength of terrestrial magnetismand the magnetic field strength becomes small. Still further, since themagnetic field strength is set at 5 Oe at least, first and second bridgecircuits 13 and 14 generate the outputs above a certain strength.Because of the above reasons, it is desirable that the magnetic fieldstrength of first and second application parts 16 and 17 is set in arange of 5 to 20 Oe.

When a narrower dispersion is required in detecting a direction, therange of the magnetic field strength needs to be further limited. Forexample, when a 5° of directional dispersion is required, the magneticfield strength is set between 6.0 and 18.0 Oe, or more preferablybetween 7.5 and 15.0 Oe.

If CoPt alloy is employed for first and second application parts 16 and17, the thickness of the application parts can be made smaller, toaround 500 nm. In this case, the strength of the bias magnetic field isstabilized because of small dispersion of the thickness.

If ferrite is employed for first and second application parts 16 and 17,cost of application parts 16 and 17 can be reduced.

Next, a production method of the direction sensor in accordance with thefirst exemplary embodiment of the present invention will be described.

First, first detecting element 12A to eighth detecting element 12H,input electrodes 18A and 18B, ground electrodes 19A and 19B, and firstoutput electrode 20A to fourth output electrode 20D are formed on theupper surface of substrate 11. To form them, a method such as a printingor a vapor deposition is used.

At this time, first bridge circuit 13 is formed with first detectingelement 12A to fourth detecting element 12D, as well as forming inputelectrode 18A, ground electrode 19A, first output electrode 20A andsecond output electrode 20B respectively at predetermined positions.Similarly, second bridge circuit 14 is formed with fifth detectingelement 12E to eighth detecting element 12H, as well as forming inputelectrode 18B, ground electrode 19B, third output electrode 20C andfourth output electrode 20D at respective positions.

Next, insulating layer 15A is formed on the upper surface of firstbridge circuit 13 as well as forming insulating layer 15B on the uppersurface of second bridge circuit 14. As previously mentioned, insulatinglayer 15A is formed covering first detecting element 12A to fourthdetecting element 12D, and insulating layer 15B covering fifth detectingelement 12E to eighth detecting element 12H.

Then, first magnetic bias application part 16 is formed on the upperpart of insulating layer 15A as the part facing toward first bridgecircuit 13, by a printing or an etching method, as well as formingsecond magnetic bias application part 17 on the upper part of insulatinglayer 15B, facing toward second bridge circuit 14. Then, magneticfield-generating coils are approximated to first and second applicationparts 16 and 17 for establishing the magnetic fields directed in certaindirections.

In this process, longitudinal directions of first detecting element 12Ato eighth detecting element 12H are arranged so as to cross the magneticfields produced by first and second application parts 16 and 17 at anangle of 45°, and the magnetic field directions produced by first andsecond application parts 16 and 17 are to be directed about 90°different from each other, as shown in FIG. 3.

It is desirable that first and second application parts 16 and 17 areformed by a liftoff method; thereby insulating layer 15A, insulatinglayer 15B, first and second bridge circuits 13 and 14 are prevents frombeing damaged.

Namely, a resist is applied at a place where first and secondapplication parts 16 and 17 are not to be formed, next magneticmaterials forming first and second application parts 16 and 17 areapplied on an entire surface of insulating layers 15A, 15B, and then theresist is removed, forming first and second application parts 16 and 17at their predetermined positions. In this process, unnecessary magneticmaterial is removed when the resist is removed. It is not necessary toremove the unwanted magnetic material selectively as is required by theetching method. Therefore, bridge circuits 13 and 14 and insulatinglayers 15A and 15B are prevented from being attached or penetrated byetching liquid.

Especially when CoPt alloy is etched for forming first and secondapplication parts 16 and 17, a strong acid of etching liquid is used.The etching liquid damages insulating layers 15A and 15B or first andsecond bridge circuits 13 and 14, deteriorating humidity resistance andsacrificing reliability. By using the liftoff method, these problems areavoided and a high reliability direction sensor is provided.

In this exemplary embodiment, the magnetic fields are aligned afterfirst and second application parts 16 and 17 are formed. By doing so,the magnetic fields of first and second application parts 16 and 17 aresimultaneously or successively aligned so that productivity is improved.In the placing process, a magnet of which magnetic field has alreadyaligned can be disposed on the upper surface of insulating layers 15Aand 15B.

Lastly, cover layers 21A is formed on the upper surface of firstapplication part 16, as well as cover layer 21B being form on the uppersurface of second application part 17, by a molding method, forinstance.

Next, the working principle of the direction sensor in accordance withthe first exemplary embodiment of the present invention will beexplained.

First, a prescribed voltage is applied between input electrode 18A andground electrode 19A in first bridge circuit 13. Then, the magneticfields generated by first magnetic bias application part 16 and theterrestrial magnetism change the resistance values of first detectingelement 12A to fourth detecting element 12D. At this time, first outputelectrode 20A and second output electrode 20B output voltagescorresponding to the change of the resistance values, and differentialvoltage between the two outputs is detected. This voltage changesdepending on an angle by which the terrestrial magnetism crosses firstbridge circuit 13. The voltage changes substantially sinusoidallydependent on the angle by which the terrestrial magnetism and firstbridge circuit 13 cross.

In second bridge circuit 14, a differential output voltage changingalmost sinusoidally with an crossing angle of the terrestrial magnetismand second bridge circuit 14 is similarly detected between third outputelectrode 20C and fourth output electrode 20D.

In this instance, the magnetic field direction of first application part16 and that of second application part 17 are different by 90°, namely aphase of one differential output voltage is shifted by 90° from that ofanother differential another voltage. Assuming an angle of direction asθ, one output voltage is represented by A sin θ and another isrepresented by A′ cos θ. Standardized by amplitude A and A′, tan θ, anoutput ratio between the two, is given out, easily identifying thedirection θ. If a variation of the magnetic field strength of both ofthe magnetic application parts is controlled so as to make bothamplitudes identical, the standardization process is unnecessary.

At this time, the magnetic field directions being generated by first andsecond application parts 16 and 17 are controlled so that dispersion ofmeasured directional angle θ is restricted within a prescribed range,for instance 7°. In this exemplary embodiment, an angle between magneticfield directions 31 and 32 produced by first and second applicationparts 16 and 17 is made to be around 90°. However, the angle does notneed to be 90°. As long as the magnetic field directions of first andsecond application parts 16 and 17 are different, the outputs from firstand second bridge circuits 13 and 14 are out of phase with respect toeach other. Because the output from first bridge circuit 13 changessinusoidally, a same output value is measured in two directional angles.However, one direction is finally identified with a sign of differencebetween the output from first bridge circuit 13 and that of secondbridge circuit 14. Thus, all directions from 0° to 360° are identified.At this time, the directions of the magnetic fields of first and secondbridge circuits 13 and 14 have to be differentiated so that the phase ofthe outputs may not overlap.

In this exemplary embodiment, insulating layers 15A and 15B arerespectively separated individual layers, and cover layers 21A and 21Bare also separated individual layers. Nevertheless, the layers can beintegrated as illustrated in FIG. 6.

FIG. 6 is a sectional view of another direction sensor in accordancewith the first exemplary embodiment of the present invention. Insulatinglayer 15 overlays first bridge circuit 13 and second bridge circuit 14altogether, and cover layer 21 covers first application part 16 andsecond application part 17 altogether.

Even with this constitution, a similar effect is obtained as in thedirection sensor shown in FIG. 1.

Second Exemplary Embodiment

A second exemplary embodiment of the present invention will be explainedusing FIG. 7. FIG. 7 is a sectional view of a direction sensor inaccordance with the second exemplary embodiment of the presentinvention.

In the first exemplary embodiment, components including first and secondbridge circuits are formed on one side of the substrate. Whereas, in thesecond exemplary embodiment, a first bridge circuit is formed on anupper surface of a substrate while a second bridge is formed on a undersurface of the substrate, otherwise the structure of this embodiment isidentical to that of the first exemplary embodiment.

In the following, the structure of the second exemplary embodiment isexplained.

First bridge circuit 13 is formed on an upper surface of substrate 11.First insulating layer 15A is deposited on an upper surface of firstbridge circuit 13. First magnetic bias application part 16 is disposedon an upper surface of first insulating layer 15A, facing toward firstbridge circuit 13. First cover layer 21A is formed an upper surface ofthe first magnetic bias application part 16.

Second bridge circuit 14 is formed on an under surface of substrate 11,and second insulating layer 15B is deposited on an under surface ofsecond insulating layer 15B. Second magnetic bias application part 17 isdisposed on an under surface of second insulating layer 15B, facingtoward second bridge circuit 14. On an under surface of the secondmagnetic bias application part 17, second cover layer 21B is formed.

As described, in the direction sensor in accordance with the secondexemplary embodiment of the present invention, each of first and secondbridge circuits 13 and 14 is formed on a different surface of substrate11. Because of this structure, the dimensions of a main surface aresmaller than when the first and second bridge circuits is formed on onesurface. Hence, the direction sensor can be produced smaller.Furthermore, since first and second application parts 16 and 17 areformed on different surfaces, a distance between first and secondapplication parts 16 and 17 is made larger, making a magnetic fieldinfluence of first application part 16 over second bridge circuit 14small. Likewise, a magnetic field influence of second application part17 over first bridge circuit 13 becomes small.

Third Exemplary Embodiment

A third exemplary embodiment of the present invention will be explainedusing FIG. 8. FIG. 8 is a plan view of an upper surface of first andsecond bridge circuits, main parts of a direction sensor in accordancewith the third exemplary embodiment of the present invention.

In the direction sensor of the third exemplary embodiment, magneticfield bias application parts are additionally formed around first andsecond bridge circuits 13 and 14 as seen in the plan view.

As FIG. 8 shows, magnetic bias application parts 16A, 16B, 16C and 16Dare placed around first bridge circuits 13, constituting a surroundingmagnetic bias application part. Similarly, magnetic bias applicationparts (hereinafter called an application part) 17A, 17B, 17C and 17D areplaced around second bridge circuit 14.

In this structure, one side of application part 16A facing first bridgecircuit 13 is polarized to N. One side of application part 16B facingtoward application part 16A through first bridge circuit 13 is polarizedto S. Application part 16C, disposed between application part 16A andapplication part 16B along bridge circuit 13 is polarized to N at a sidefacing application part 16A and S at a side facing application part 16B.Application part 16D facing toward application part 16C through firstbridge circuit 13 and disposed between application part 16A andapplication part 16B is polarized to N at a side facing application part16A and S at a side facing application part 16B.

Application parts 17A to 17D are disposed around second bridged circuit14; their magnetic fields are rotated 90° clockwise relative to those ofapplication parts 16A to 16D.

The direction sensor in the third exemplary embodiment is constituted byadding application parts 16A to 16D and 17A to 17D to the directionsensor of the first exemplary embodiment. In other words, firstapplication part 16 and second application part 17 are respectivelypositioned upward of first bridge circuit 13 and second bridge circuit14, though it is not illustrated in the drawing. In this structure, themagnetic field direction of first application part 16 is to N at itsleft side and S at its right side, as shown by arrow mark 81 in FIG. 8.The magnetic field direction of second application part 17 is to N atthe upside and S at the down side, as shown by arrow mark 82.

With this structure, it is hard for the magnetic field to leak out of aspace surrounded by application parts 16A to 16D. Because of its highefficiency of magnetic field application to first bridge circuit 13, theapplication parts 16 and 16A to 16D can function even when the magneticfield strength of the magnets of application parts 16 and 16A to 16D isweak. By constituting so, a probability that the magnetic field appliedto first bridge circuit 13 may affect second bridge circuit 14 remainslow. Application parts 17A to 17D work similarly.

Above, the first to third exemplary embodiments of the present inventionare explained. In addition, because a holder or a coil is not requiredfor the structures, the direction sensors can be manufactured small.Still further, because the permanent magnets are used for generating thebias magnetic field instead of energization of a coil, the directionsensors do not require electric power of producing the magnetic fields,so that energy is saved. This type of detection sensor can be installedon a mobile device or the like.

In all the above embodiments, the first detecting circuit and the seconddetecting circuit respectively employ a bridge circuit composed of fourdetecting elements for detecting a differential voltage. On the otherhand, the first detecting circuit and the second detecting circuit canbe composed of a half bridge circuit using two detecting elements. Thehalf bridge circuit will be explained as follows using FIG. 9. FIG. 9 isa circuit diagram of a varied type of the first detecting circuit of thedirection sensor according to the present invention.

First detecting circuit 90 is composed of first detecting element 12Aand second detecting element 12B. In first detecting circuit 90, aprescribed voltage is applied between first input electrode 18A andground electrode 19A then a differential voltage between first outputelectrode 20A and ground electrode 19A is detected. Because the circuitis half of the bridge circuit, it is called a ‘half bridge circuit.’

A positional relationship between first detecting element 12A and seconddetecting element 12B and a positional relationship between thedetecting elements and the magnetic field direction of the firstmagnetic bias application part facing against first detecting circuit 90are identical to those in the first exemplary embodiment.

The second detecting circuit can be similarly constituted.

The circuitry of the half bridge circuit of this kind requires half thenumber of the detecting elements required for the bridge circuit. Hence,a required dimension is small and the circuit is simple, and thereforeadvantageous for miniaturization.

INDUSTRIAL APPLICABILITY

As mentioned above, the direction sensor according to the presentinvention has the following constituents:

a substrate,

a first detecting circuit having at least two detecting elements formedon a main surface of the substrate; and a second detecting circuithaving an identical structure,

a first magnetic bias application part disposed facing toward the firstdetecting circuit,

a second magnetic bias application part disposed facing toward thesecond detecting circuit, and generating a magnetic field in a directiondifferent from that of the first magnetic bias application part.

This structure does not require a holder or a coil, thereby a feasibleminiaturized direction sensor is obtained.

1. A direction sensor comprising: a substrate; a first detecting circuitformed on the substrate and including at least two detecting elements; asecond detecting circuit formed on the substrate and including at leasttwo detecting elements; a first magnetic bias application part disposedfacing toward the first detecting circuit, the first magnetic biasapplication part operable to apply a magnetic bias to the firstdetecting circuit by producing a magnetic field; and a second magneticbias application part disposed facing toward the second detectingcircuit, the second magnetic bias application part operable to apply amagnetic bias to the second detecting circuit by producing a magneticfield having a direction that is different from a direction of themagnetic field produced by the first magnetic bias application part,wherein the first detecting circuit includes: a first detecting elementhaving a longitudinal pattern direction; a second detecting elementhaving a longitudinal pattern direction that is different from thelongitudinal pattern direction of the first detecting element, thesecond detecting element being electrically connected to the firstdetecting element in series; a third detecting element having alongitudinal pattern direction that is in parallel with the longitudinalpattern direction of the second detecting element; and a fourthdetecting element having a longitudinal pattern direction that is inparallel with the longitudinal pattern direction of the first detectingelement, the fourth detecting element being electrically connected tothe third detecting element in series, wherein the first detectingelement and the second detecting element in series are electricallyconnected in parallel to the third detecting element and the fourthdetecting element series, wherein the second detecting circuit includes:a fifth detecting element having a longitudinal pattern direction; asixth detecting element having a longitudinal pattern direction that isdifferent from the longitudinal pattern direction of the fifth detectingelement, the sixth detecting element being electrically connected to thefifth detecting element in series; a seventh detecting element having alongitudinal pattern direction that is in parallel with the longitudinalpattern direction of the sixth detecting element; and an eighthdetecting element having a longitudinal pattern direction that is inparallel with the longitudinal pattern direction of the fifth detectingelement, the eighth detecting element being electrically connected tothe seventh detecting element in series, and wherein the fifth detectingelement and the sixth detecting element are electrically connected inparallel, and the seventh detecting element and the eighth detectingelement are electrically connected in parallel.
 2. The direction sensoraccording to claim 1, wherein a direction of the magnetic field producedby the first magnetic bias application part and a direction of themagnetic field produced by the second magnetic bias application part are90° apart, wherein the longitudinal pattern direction of the firstdetecting element and the longitudinal pattern direction of the seconddetecting element are 90° apart, and wherein the longitudinal patterndirection of the fifth detecting element and the longitudinal patterndirection of the seventh detecting element are 90° apart.
 3. Thedirection sensor according to claim 2, wherein the direction of themagnetic field produced by the first magnetic bias application part andthe longitudinal pattern direction of the first detecting element are45° apart, and wherein the direction of the magnetic field produced bythe second magnetic bias application part and the longitudinal patterndirection of the fifth detecting element are 45° apart.
 4. A directionsensor comprising: a substrate; a first detecting circuit formed on thesubstrate and including at least two detecting elements; a seconddetecting circuit formed on the substrate and including at least twodetecting elements; a first magnetic bias application part disposedfacing toward the first detecting circuit, the first magnetic biasapplication part operable to apply a magnetic bias to the firstdetecting circuit by producing a magnetic field; and a second magneticbias application part disposed facing toward the second detectingcircuit, the second magnetic bias application part operable to apply amagnetic bias to the second detecting circuit by producing a magneticfield having a direction that is different from a direction of themagnetic field produced by the first magnetic bias application part,wherein the first detecting circuit includes: a first detecting elementhaving a longitudinal pattern direction; and a second detecting elementhaving a longitudinal pattern direction that is different from thelongitudinal pattern direction of the first detecting element, thesecond detecting element being electrically connected to the firstdetecting element in series, wherein the second detecting circuitincludes: a third detecting element having a longitudinal patterndirection; and a fourth detecting element having a longitudinal patterndirection that is different from the longitudinal pattern direction ofthe third detecting element, the fourth detecting element beingelectrically connected to the third detecting element in series.
 5. Adirection sensor comprising: a substrate; a first detecting circuitformed on the substrate and including at least two detecting elements; asecond detecting circuit formed on the substrate and including at leasttwo detecting elements; a first magnetic bias application part disposedfacing toward the first detecting circuit, the first magnetic biasapplication part operable to apply a magnetic bias to the firstdetecting circuit by producing a magnetic field; and a second magneticbias application part disposed facing toward the second detectingcircuit, the second magnetic bias application part operable to apply amagnetic bias to the second detecting circuit by producing a magneticfield having a direction that is different from a direction of themagnetic field produced by the first magnetic bias application part,wherein the first detecting circuit is formed on a first surface of thesubstrate and the second detecting circuit is formed on a second surfaceof the substrate opposite to the first surface.